Internal combustion engine

Abstract

To provide a technique capable of thinning an oil pan without impairing certainty of injection of oil in a slant type internal combustion engine in which a cylinder bore is largely inclined to a horizontal side.SOLUTION: A depression portion of a lower end portion of a crankcase 8 is formed as a flange-shaped thick rearward projecting portion 23. As viewed in a crankshaft axis direction, an oil pan 9 extends over substantially the entire length of the crankcase 8. A backward projecting part 23 of the crankcase 8 is provided with an upward projecting part 23a, and a downward extending part side 10a of a chain cover 10 is fastened to the upward projecting part 23a by a bolt 33. A pocket-like space 28 between the crankcase 8 and the oil pan 9 has an upward bulging part 28a, and the upward bulging part 28a and an internal space of the chain cover 10 are communicated with each other by a vent hole 29 and paths 30, 31. Since air in the upward bulging part 28a is removed from the paths 30, 31, oil can be fully injected.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine, and is preferably directed to an internal combustion engine for an automobile. [Background technology]

[0002] Internal combustion engines, such as gasoline internal combustion engines, are equipped with an oil pan that stores lubricating oil. By its very nature, the oil pan is disposed horizontally on the underside of the cylinder block. In the case of in-line internal combustion engines for automobiles, the orientation of the cylinder bores can be roughly classified into three types: a vertical type in which the cylinder bores are positioned nearly vertically; a slant type in which the cylinder bores are tilted toward the horizontal at a large angle (for example, an included angle of 50° or less with respect to the horizontal) (see, for example, Patent Documents 1 to 3); and a horizontal type in which the cylinder bores are positioned nearly horizontally.

[0003] In the case of a vertical internal combustion engine, the crankcase is formed integrally with the cylinder block, and the oil pan is fixed to the underside of the crankcase, but in the case of a slant type, the crankcase is formed separately from the cylinder block body, and the oil pan is fixed to the underside of the crankcase.

[0004] The existence of slant-type internal combustion engines for automobiles is mainly due to the problem of installation space, and in cab-over automobiles, the cylinder bore is often tilted significantly toward the horizontal side.

[0005] Even in slant-type internal combustion engines, the vertical height margins of the mounting space vary, and in Patent Document 3, in a situation where the oil pan cannot be made deep due to height restrictions in the mounting space, a separate reservoir for storing oil is provided, the lower end of the reservoir is connected to the oil pan, and the upper end of the reservoir is connected to the oil pan by an air passage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-165386 [Patent Document 2] Japanese Patent Application Publication No. 05-60015 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-220009 Summary of the Invention [Problem to be solved by the invention]

[0007] When the depth of the oil pan is limited due to installation space constraints, one method of ensuring the required amount of oil is to provide a reservoir that is a separate component from the oil pan, as in Patent Document 3. However, providing a separate reservoir can complicate the structure, increasing costs and making assembly more time-consuming. There is also the concern that poor oil flow response between the oil pan and reservoir may cause the oil level to drop in the oil pan even though the required amount of oil is present overall, resulting in air being sucked into the strainer.

[0008] Furthermore, since reservoirs tend to be less rigid than oil pans, there is concern that in the event of an accident, the reservoir may be more susceptible to damage, leading to oil leaks and making the vehicle unable to move under its own power.

[0009] Therefore, it is preferable to have only an oil pan as the oil storage means, but if only an oil pan is used, the flat area must be large to secure the necessary oil storage container, which may cause problems such as the oil not being able to be distributed evenly when injected.

[0010] The present invention was made against this background, and aims to allow the oil pan to retain its oil storage function alone without compromising the reliability of oil injection, even in situations where the oil pan cannot be made deeper. [Means for solving the problem]

[0011] The internal combustion engine of the present invention comprises: "The engine body includes a cylinder block, an oil pan fixed to the underside of the cylinder block, and a chain cover fixed to one end face of the cylinder block, The cylinder block has cylinder bores that are tilted significantly toward the horizontal, and the lower end has a depression angle (inner corner) and an elevation angle (outer corner) when viewed from the crankshaft direction, while the oil pan extends over almost the entire lower surface of the cylinder block when viewed from the crankshaft direction, and a pocket-like space is formed between the depression angle of the cylinder block and one end of the oil pan. In this basic configuration, "The pocket-like space and the internal space of the engine body are in communication with each other through an air vent passage." In the present invention, the cylinder bore being inclined significantly toward the horizontal side means that the cylinder bore is inclined at an angle of about 45 degrees or greater relative to the horizontal, and "about 45 degrees" also includes 55 degrees.

[0012] The present invention can be embodied in various ways. For example, claim 2 states: The pocket-like space has an upward bulge due to the depression of the cylinder block, and a part of the chain cover overlaps with the upward projection of the depression of the cylinder block. The chain cover is formed with the air vent passages as follows: a first passage communicating with the upwardly bulging portion of the pocket-like space; and a second passage communicating with the first passage and opening into the internal space of the chain cover. The structure is as follows.

[0013] Since the internal combustion engine of the present invention is a slant type, the cylinder block is composed of a main body in which the cylinder bores are formed and a crankcase fixed to the bottom surface of the main body. Therefore, the cylinder block also includes the crankcase fastened to the main body with bolts. [Effects of the Invention]

[0014] In the present invention, the oil pan has a large planar area, so even if it is shallow, the necessary amount of oil can be secured. Furthermore, because oil is stored solely in the oil pan, costs can be reduced and assembly work can be simplified compared to the case where a reservoir is provided as in Patent Document 3. Furthermore, because the freedom of oil flow during operation is not impeded, problems such as air suction, even when the necessary amount of oil is present, do not occur. Furthermore, because the large oil pan is integrated with the cylinder block and reinforces each other, the rigidity of the power plant (engine body) can be improved, contributing to the suppression of vibration.

[0015] On the other hand, if one end of the oil pan extends to the depressed corner of the cylinder block, the depressed corner of the cylinder block must have a specified thickness, and therefore the space enclosed by the depressed corner of the cylinder block and one end of the oil pan may become a closed pocket-like space.This may result in problems when pouring oil into the oil pan, such as poor air escape in the pocket-like space, making the pouring process difficult, or, if the pocket-like space bulges upward, causing improper pouring.

[0016] In contrast, in the present invention, the pocket-shaped space is connected to the internal space of the engine body via the air vent passage, so air does not remain trapped in the pocket-shaped space and oil can be quickly stored to a predetermined height. Therefore, in the present invention, the required amount of oil can be quickly poured into a large oil pan without causing problems such as increased costs.

[0017] In the present invention, a pipe can be used as the air vent passage, which has the advantage of providing excellent flexibility in the placement of the air vent passage. In contrast, if the configuration of claim 2 is adopted, the air vent passage is formed in a component of the internal combustion engine, which reduces costs and eliminates the labor required for installation. There is no risk of objects getting caught, and reliable operation is ensured. Furthermore, because the air vent passage is formed as a hole, it contributes to improved fuel economy by reducing weight.

[0018] Now, by providing an upward convex portion at the depressed corner of the cylinder block as in claim 2, it is possible to improve rigidity against bending and increase the amount of oil that can be stored. However, if there is an upward bulge in the pocket-like space, there is a risk that vibrations and shaking during operation will cause the air in the upward bulge to turn into bubbles, which will float in the oil and be sucked into the strainer.

[0019] In contrast, in the present invention, the air in the upward bulge can be discharged into the inside of the engine body, thereby increasing the amount of oil stored without compromising the reliability of oil injection, and preventing the air in the upward bulge from turning into bubbles and entering the oil, thereby preventing the air intake phenomenon caused by the presence of the upward bulge. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a rear view of the internal combustion engine according to the embodiment. [Figure 2] FIG. 2 is a rear view of the internal combustion engine as seen from the rear side of the vehicle body. [Figure 3] FIG. 2 is a side view of the internal combustion engine as seen from the side of the vehicle body. [Figure 4] FIG. 2 is a perspective view showing the appearance of a main part as viewed from the side. [Figure 5] FIG. 2 is a cutaway perspective view seen from the side with the chain cover removed. [Figure 6] FIG. 4 is a cutaway perspective view seen from the side with the air vent passage displayed. [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII in FIGS. 3 and 6. [Figure 8] FIG. 2 is a diagram showing a state in which an internal combustion engine is mounted on a vehicle body. DETAILED DESCRIPTION OF THE INVENTION

[0021] (1) Vehicle installation and basic structure Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a three-cylinder internal combustion engine for an automobile. As shown in FIG. 8, the internal combustion engine is disposed in a rear compartment (rear internal combustion engine room) 2 provided at the rear of a vehicle body 1. A front compartment 3 is formed at the front of the vehicle body, and a battery, a motor, etc. are disposed in the front compartment 3. Therefore, the automobile to which this embodiment is applied is a hybrid vehicle.

[0022] As described above, the internal combustion engine is disposed in the rear compartment 2, but as shown in Figures 1 and 3, the cylinder bore axis O1 is inclined at an angle of approximately 45° with respect to the vertical and horizontal. That is, the internal combustion engine is mounted transversely with the crankshaft 4 elongated in the vehicle width direction, but is tilted backward with the crankshaft 4 located on the front side of the vehicle body and the cylinder head located on the rear side. Therefore, the internal combustion engine of this embodiment is a transversely mounted slant-type internal combustion engine inclined toward the rear of the vehicle body.

[0023] In the following, the terms "front / rear" and "left / right" are used to specify directions, but these terms "front / rear" and "left / right" are based on the orientation of the vehicle body (driver). In internal combustion engines, the direction of the crankshaft is often defined as the front / rear direction, but the directions used in this embodiment differ from this general definition. The up / down direction is the direction of a vertical line. Directions are clearly indicated in the drawings as appropriate. In Figure 5, the dotted hatching indicates a flat surface, not a cross section.

[0024] The basic structure of an internal combustion engine is the same as that of a conventional engine, and as shown in Figures 1 and 3, the engine body comprises a cylinder block body 5 in which cylinder bores (not shown) are formed, a cylinder head 6 fixed to the top surface of the cylinder block body 5, and a head cover 7 fixed to the top surface of the cylinder head 6. Because the cylinder bore axis O1 is inclined significantly rearward, a crankcase 8 that is triangular in side view is fixed to the underside of the cylinder block body 5, as shown in Figure 1. Therefore, the cylinder block is made up of the cylinder block body 5 and the crankcase 8.

[0025] An oil pan 9 is fixed to the underside of the crankcase 8. As shown in Figures 1 and 3, the oil pan 9 has a uniform depth throughout and extends over almost the entire length of the crankcase 8 when viewed from the side (as viewed in the direction of the crank axis). However, the oil pan 9 is much shallower than that of a typical internal combustion engine.

[0026] That is, the internal combustion engine is mounted in the rear compartment 2 of the vehicle as shown in Fig. 8, but because the height of the rear compartment 2 is restricted significantly, the oil pan 9 has a single structure and is therefore shallower and has a larger area than that of a normal internal combustion engine in order to ensure the necessary capacity. Note that, as shown in Fig. 2, when viewed from behind, the oil pan 9 has a width that is about half the width of the cylinder block main body 5.

[0027] For example, as shown in Figure 3, a chain cover 10 that covers a timing chain (not shown) is fixed with a number of bolts to the left end faces of the cylinder block body 5, crankcase 8, and cylinder head 6. On the other hand, as shown in Figure 1, the right end face of the cylinder block 5 forms a transmission case mounting flange 11.

[0028] In Figure 1, reference numeral 12 denotes a catalyst case, which is covered with an insulator 13. Reference numeral 14 denotes an exhaust joint pipe connected to the catalyst case 12. Reference numeral 15 denotes an air cleaner, and reference numeral 16 denotes a surge tank for the intake manifold. In Figure 3, reference numeral 17 denotes a water pump, and a hose for the radiator return passage is connected to a cylinder 17a at the upper end.

[0029] In this embodiment, the oil pump (trochoid pump) is driven by the crankshaft 4, and although not shown, a pump housing is formed in the chain cover 10, and the pump housing is covered from the inside by a pump cover, forming a pump chamber between them. As shown in FIG. 3, an oil filter base 18a is provided in the front portion of the chain cover 10 across the crankshaft 4, and an oil filter 18 is screwed into this from below. In FIG. 3, reference numeral 19 denotes a boss portion (ridge-like portion) for forming an oil passage, and reference numeral 20 denotes a crank pulley. In FIG. 2, reference numeral 21 denotes the head of the ignition coil.

[0030] Although not shown, an oil filler port closed by an oil cap is provided in a portion of the head cover 7 located above the oil pan 9. The oil can flow from the valve chamber down to the oil pan 9 via an oil drop passage, or it can flow down to the oil pan 9 by utilizing the space in which the timing chain is located. The oil filler port can also be provided in the cylinder block body 5 or the cylinder head 6.

[0031] (2) Details of the oil pan For example, as shown in FIGS. 4 to 6, an outward flange 9 a is formed at the upper end of the oil pan 9 , and the flange 9 a is fixed to the lower surface of the crankcase 8 by a number of bolts 22 .

[0032] The crankcase 8 is provided because the internal combustion engine is a slant type that is tilted horizontally. Because the internal combustion engine is a slant type, the lower end has a depression angle portion (inner corner portion) that tends to be hidden on the horizontal side, and an elevation angle portion (outer corner portion) that is open and extends upward from the horizontal. In this embodiment, the depression angle portion and the elevation angle portion are configured as the ends of the crankcase 8.

[0033] 4 to 6, the rear end of crankcase 8 forms a flange-shaped rearward protruding portion 23, and the front end of crankcase 8 forms a forward protruding portion 24. Since oil pan 9 overlaps almost the entire crankcase 8 in a side view, oil pan 9 also has a rearward extending portion 9b that overlaps rearward protruding portion 23 of crankcase 8.

[0034] Looking at it from another perspective, the rear end of the crankcase 8 protrudes rearward from the lower end of the rear side surface of the cylinder block main body 5, and the part that protrudes rearward forms a rearward protruding portion 23 (in side view (viewed in the direction of the crank axis), the rear surface of the cylinder block main body 5 and the rearward protruding portion 23 of the crankcase 8 form a sideways V-shape (or an oblique L-shape)).

[0035] Figure 5 partially shows the positional relationship between the cylinder block body 5 and the crankcase 8. In Figure 5, reference numeral 25 indicates the mating surface between the cylinder block body 5 and the crankcase 8, and it can be clearly seen that the rearward protruding portion 23 of the crankcase 8 protrudes rearward from the lower end of the cylinder block body 5.

[0036] 5, the mating surfaces 26, 27 between the crankcase 8 and the cylinder block main body 5 and where the chain cover 10 meet are shown by dotted hatching, but by comparing Figure 5 with Figure 4, it can be seen that the mating surfaces 26, 27 between the crankcase 8 and the cylinder block main body 5 and where the chain cover 10 meet extend to the right of the left end face of the crankcase 8. In relation to this, it can be seen from Figure 4 that the left end of the oil pan 9 protrudes to the left of the chain cover 10.

[0037] As shown in Figures 5 and 6, the rearward protruding portion 23 of the crankcase 8 and the rearward extending portion 9b of the oil pan 9 overlap, forming a pocket-like space 28 between them. Also, as shown in Figures 5 and 6, an upward protruding portion 23a is formed on the rearward protruding portion 23 of the crankcase 8, and the downward extending portion 10a of the chain cover 10 is fixed to the left side surface of the upward protruding portion 23a with a bolt 33. When the upward protruding portion 23a is provided on the crankcase 8, as shown in Figure 7, the pocket-like space 28 has an upward bulge 28a at the location of the upward protruding portion 23a.

[0038] Providing the rearward protruding portion 23 on the crankcase 8 increases the front-to-rear width of the oil pan 9 and improves the stability of the engine body, while providing the upward protruding portion 23a improves the rigidity of the rear portion of the crankcase 8, and fixing the downward extending portion 10a of the chain cover 10 improves the unity (fastening strength) between the chain cover 10 and the crankcase 8. As a result, this contributes to improving the rigidity of the power plant (engine body) including the cylinder block body 5, crankcase 8, and oil pan 9.

[0039] Regarding oil storage, in this embodiment, oil is stored in the entire space enclosed by the crankcase 8 and the oil pan 9. Therefore, the crankcase 8 also has an oil storage function, and an opening (not shown) that communicates with the crank chamber is formed in the crankcase 8. Therefore, the crankcase 8 can also be considered as an upper oil pan.

[0040] The oil level differs between the operating state and the stopped state, but in this embodiment, either a state in which the space between the crankcase 8 and the oil pan 9 is filled with oil in both the stopped state and the operating state, or a state in which the space between the crankcase 8 and the oil pan 9 is filled with oil in the stopped state and not filled with oil in the operating state, can be adopted. In the former case, the oil level is located above the bottom surface of the crankcase 8 regardless of whether the engine is operating or stopped, but in the latter case, it is also preferable to set the oil level as high as possible even in the operating state to prevent air from getting mixed in when the oil is sucked up by the strainer.

[0041] In any case, the space between the crankcase 8 and the oil pan 9 must be filled with oil at least when the engine is stopped. However, because the upward bulge 28a of the pocket-like space 28 is a space that is open only downward, if no measures are taken, air will accumulate in the upward bulge 28a when, for example, pouring oil, making it impossible to pour the required amount of oil. Furthermore, if the upward bulge 28a acts as an air trap, engine vibration or vehicle body shaking can cause the air in the upward bulge 28a to turn into bubbles, which will then get into the oil and be sucked into the strainer.

[0042] Therefore, in this embodiment, as shown in Figures 5 to 7, first, an air vent hole 29 communicating with the inside and outside is formed in the upward protrusion 23a of the crankcase 8 at the mating surface with the downward extension 10a of the chain cover 10, and then, a first passage 30 communicating with the air vent hole 29 and a vertically elongated second passage 31 communicating with the first passage 30 and opening at the upper end are formed in the downward extension 10a of the chain cover 10, as an example of the air vent passage described in the claims.

[0043] The chain cover 10 is a die-cast product, but the first passage 30 is formed during die-cast molding, while the second passage 31 is formed by drilling after molding. The second passage 31 is drilled from below, so its lower end is closed with a plug 32. The ventilation hole 29 in the crankcase 8 is formed during die-casting or casting, but can also be drilled later.

[0044] In this way, by providing the ventilation hole 29 and the first and second passages 30, 31, air can escape from the upward bulge 28a into the internal space of the chain cover 10, so that when oil is poured in, the upward bulge 28a can be filled with oil. On the other hand, when driving, even if the oil sways, the air in the upward bulge 28a escapes into the internal space of the chain cover 10, so there is no chance that the air in the upward bulge 28a will turn into bubbles and get into the oil.

[0045] Furthermore, as in the embodiment, by forming an upward convex portion 23a on the rearward protruding portion 23 of the crankcase 8 and providing an upward bulge portion 28a in the pocket-like space 28, the oil storage space is extended upward, so that the amount of oil stored can be increased as much as possible even when the height of the mounting space is restricted.

[0046] 5 and 6, a group of ribs 34 that regulate the movement of oil are formed in a grid pattern extending in all directions on the bottom surface of the oil pan 9. The bottom of the crankcase 8 also has front and rear upward sections 35, 36, which are filled with oil at least when the engine is not running.

[0047] In the above embodiment, the air vent passage is formed in the chain cover 10, but the air vent passage can also be formed on the inner surface of the crankcase, or straddling the crankcase and the cylinder block body. It is also possible to arrange communication joints on the upward protrusion and the cylinder block and connect these joints with a pipe. The internal combustion engine can be mounted in an engine compartment located in the front of the vehicle, or in the space below the seat.

[0048] In addition, as a means for increasing the capacity of the oil pan, it is also possible to extend the elevation portion to increase the planar area, or to provide an upward bulge portion on the elevation portion. [Industrial Applicability]

[0049] The present invention can be embodied in an internal combustion engine and is therefore industrially applicable. [Explanation of symbols]

[0050] 1. Body 2 rear compartment 4 crankshaft 5 Cylinder block body 6. Cylinder head 8 Crankcase 9 Oil pan 9b Rearward extension 10 Chain cover 10a Downward extension 23 Rearward protruding part of crankcase (depression corner, inner corner) 23a upward convex part 24 Forward protruding part of crankcase (elevation part, outer corner part) 25 Mating surface between crankcase and cylinder block body 26 Crankcase and chain cover mating surface 27 Mating surface between cylinder block body and chain cover 28 Pocket-like space 28a Upward bulge 29 Ventilation holes 30 1st aisle 31 2nd aisle 32 plug

Claims

1. The engine body includes a cylinder block, an oil pan fixed to a lower surface of the cylinder block, and a chain cover fixed to one end surface of the cylinder block, an internal combustion engine in which the cylinder block has cylinder bores that are tilted significantly toward the horizontal side and a lower end portion thereof, as viewed from the crankshaft direction, having a depressed portion and an elevated portion; and the oil pan extends over substantially the entire lower surface of the cylinder block as viewed from the crankshaft direction, and a pocket-like space is formed between the depressed portion of the cylinder block and one end of the oil pan, the pocket-like space and the internal space of the engine body are in communication with each other through an air vent passage; Internal combustion engine.

2. the pocket-like space has an upwardly bulging portion due to an upwardly protruding portion of the depression corner portion of the cylinder block, and a portion of the chain cover overlaps with the upwardly protruding portion of the depression corner portion of the cylinder block, The chain cover is formed with a first passage communicating with the upwardly bulging portion of the pocket-like space and a second passage communicating with the first passage and opening into the internal space of the chain cover as the air vent passage.

2. An internal combustion engine according to claim 1.

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